introduction to cells Flashcards
3 facts about the cell theory
- All living things are composed of cells
- the cell is the smallest unit of life
- cells only arise from pre-existing cells
exceptions to cell theory
- Skeletal muscle - much larger fibres (like cells) then normal
- Giant Algae - contain only single nucleus so not multicellular
- aseptate fungi - long undivided sections of hypha which contain many nuclei
what are unicellular organisms?
Unicellular organisms consist of only one cell and carry out all functions of life in that cell
7 basic functions integral to survival
- Metabolism - chemical reactions undertaken
- Reproduction - produce offspring (sexually or asexually)
- Sensitivity - responsive to internal and external stimuli
- Homeostatis - maintaining a stable internal environment
- Excretion - removal of waste products
- Nutrition - exchange materials and gases with environment
- Growth - move and changing shape or size
2 examples of unicellular organisms:
- Paramecium
- Chlamydomonas
paramecium 7 basic functions
Mr Sheng
1. produces enzymes which catalyse many different chemical reactions in the cytoplasm
2. reproduce asexually using mitosis or sexually using meiosis and gametes
3. reacts to stimuli
4. keep internal conditions within limits
5. expels waste products of metabolism
6. feed on smaller organisms by ingesting and digesting through vescicles
7. increase in size and mass by accumulating organic matter and minerals from its food
Chlamydomonas 7 basic functions
Mr Sheng
1.produces enzymes which catalyse many different chemical reactions in the cytoplasm
2.reproduce asexually using mitosis or sexually using meiosis and gametes
3. reacts to stimuli
4. keep internal conditions within limits
5. expels waste products of metabolism
6. Produces its own food by photosynthesis using a chloroplast that occupies much of the cell
7. increase in size and mass due to photosynthesis and absorption of minerals
production of chemical energy by cells
cells need to produce chemical energy (via metabolism) to survive and this requires the exchange of materials with the environment
multicellular organisms
Large organisms are multicellular since they consist of many cells
advantages of multicellular organisms
- division of labour (different groups of cells/tissues become specialized for different functions by the process of differentiation)
metabolism
function of its mass / volume
rate of material exchange
function if its surface area
surface area to volume ratio
surface area ÷ by volume
calculation of magnification
magnification = Image size ÷ Actual size
light microscope
light microscopes use visible light and a combination of lenses to magnify images of mounted specimens
what are emergent properties
emergent properties arise when the interaction of individual component produce new functions
multicellular organism functions
- Cells may be grouped together to form tissues
- Organs are then formed from the functional grouping of multiple tissues
- Organs that interact may form organ systems capable of carrying out specific body functions
- Organ systems collectively carry out the life functions of the complete organism
organisation of Mulicellular organisms
from: Muscle (cell) -> Cardia (Tissue) -> Heart (organ) -> Vascular (system) -> Human (organism)
differentiation
process during development whereby newly formed cells become more specialized and distinct from one another as they mature
how is chromatin formed?
Within the nucleus of a eukaryotic cell, DNA is packaged with proteins to form chromatin.
gene packaging
- active genes are packed in an euchromatin
- inactive genes have different regions of DNA packaged as euchromatin and heterochromatin
stem cells qualities:
- self renewal - continuously divide and replicate
- Potency - capacity to differentiate into specialised cell types
types of stem cells
- Totipotent - can form any cell type as well as extra embryonic tissue
- Pluripotent - can form any cell type
- Multipotent - can differentiate into a number of closely related cell types
- Unipotent - can not differentiate, but can self renew
what are stems cells necessary for?
stem cells are necessary for embryonic development as they are an undifferentiated cell source from which all other cell types may be derived
